Industrial applications involving use of batteries in oil wells and exploration provide an environment where a wide range of temperatures may be encountered. For example, a rig in the North sea may require that the batteries give adequate performance on the surface, as well as providing the longevity of operation required "down hole" in the oil well's high temperature environment. In industrial applications such as the "down hole" pressure measurement market and other oil applications, a high energy density battery is preferred to optimize performance and should be operable over a temperature range of from about 0.degree. C. to about 180.degree. C. However, current power source technology heretofore available does not offer a high energy density battery consistently operable over the wide temperature range.
It has been reported that with some high temperature batteries, the oil rig operators are forced to heat the tool containing the batteries on the surface prior to going "down hole". This tends to be a burdensome process and potentially dangerous since the batteries can explode. Further, surface heating generally eliminates surface testing of the equipment prior to placement in the hole.
Several batteries are currently available which claim high temperature performance. One such commercially available cell used in high temperature industrial applications today is the zinc silver oxide battery. The zinc silver oxide cell exhibits a good operating temperature range from about room temperature to approximately 180.degree. C. However, the cell is of low energy density as compared to lithium and delivers only about 1 to 11/2 volts. Consequently, those using this cell in the industry incur high costs in terms of the number of cells required in the battery and increased space requirements for these large number of cells.
Other batteries designed for use in high temperature (over 150.degree. C.) industrial applications include the lithium/oxyhalide batteries and the lithium/copper oxyphosphate battery. However, these batteries may be of limited use since they work well at high temperatures but may not work well at low temperatures (25.degree. C. and lower) as does the cell of the present invention.
Conventional lithium batteries such as those disclosed in U.S. Pat. Nos. 3,536,532, 3,700,502 and 4,271,242 are operable up to about 150.degree. C. and at higher temperatures are unstable because of excessive internal pressure generation. Alkaline batteries are generally utilized in applications having operational temperature ranges of about 100.degree.-110.degree. C. However, at elevated temperature levels such as 180.degree. C. alkaline batteries are inoperative.
Therefore, a high energy density battery of consistent performance predictability over a wide temperature range is needed for industrial applications.